It's 18% of the budget, moron. The discretionary budget is irrelevant. The entire budget is discretionary. Douchbags like you try to make the number seem bigger by comparing it with the so-called discretionary budget. What makes you believe the defense budget is "discretionary?"
You are not making any sense at all.
First of all, you are not supposed to include non-discretionary things like Social Security because they not only mandated by law and not up for any vote, but they are self funding. It would make no sense to include something that actually generates a surplus, like Social Security did for half a century, into the budget.
There are lots of things that are not supposed to be included in the national budget, because they are mandatory and can not be voted on. The interest on the national debt is another. By law that is supposed to just be paid, without any debate.
That fact that the ENTIRE national debt has also always been for the military actually makes leaving the national debt out hide military spending.
But all military spending other than on the national debt interest payments ARE discretionary.
We could survive quite well without spending a cent on the military.
The founders wanted a volunteer, citizen soldier military, and that would have been best.
It also would have been totally funded by the states and not the federal government.